A communication system, for example the wireless broadband Internet system defined by the IEEE 802.16e, acquires uplink/downlink channels between a terminal and a base station and negotiates parameters. Also, the wireless broadband Internet system transmits and receives values including power between a terminal and a base station, time, frequency offset, basic connection identifier (CID), and primary CID through a ranging process. Since a physical (PHY) layer and a media access control (MAC) layer are provided to the terminal and the base station in the above-noted communication system, a network entry process for user authentication is performed once.
However, regarding recently researched communication systems, such as the wireless broadband Internet development system, a terminal can have two predetermined frequency bandwidths (e.g., 10 MHz frequency bandwidth) based on the frequency overlay having an independent base station identifier (BSID). The communication system needs the network entry process twice since the terminal and the base station respectively have two PHY layers and MAC layers. In this instance, when a user authorization process is performed each time a network entry processed is performed, key management for handover and authorization can be problematic.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.